for supposing that male bees primordially collected pollen as well as
the females; although we have some reason to suspect that male mammals
primordially suckled their young as well as the females. Lastly, in all
cases of reversion, characters are transmitted through two, three, or
many more generations, and are then developed under certain unknown
favourable conditions. This important distinction between transmission
and development will be best kept in mind by the aid of the hypothesis
of pangenesis. According to this hypothesis, every unit or cell of the
body throws off gemmules or undeveloped atoms, which are transmitted to
the offspring of both sexes, and are multiplied by self-division. They
may remain undeveloped during the early years of life or during
successive generations; and their development into units or cells, like
those from which they were derived, depends on their affinity for, and
union with other units or cells previously developed in the due order
of growth.
INHERITANCE AT CORRESPONDING PERIODS OF LIFE.
This tendency is well established. A new character, appearing in a
young animal, whether it lasts throughout life or is only transient,
will, in general, reappear in the offspring at the same age and last
for the same time. If, on the other hand, a new character appears at
maturity, or even during old age, it tends to reappear in the offspring
at the same advanced age. When deviations from this rule occur, the
transmitted characters much oftener appear before, than after the
corresponding age. As I have dwelt on this subject sufficiently in
another work (33. The Variation of Animals and Plants under
Domestication, vol. ii. 1868, p. 75. In the last chapter but one, the
provisional hypothesis of pangenesis, above alluded to, is fully
explained.), I will here merely give two or three instances, for the
sake of recalling the subject to the reader s mind. In several breeds
of the Fowl, the down-covered chickens, the young birds in their first
true plumage, and the adults differ greatly from one another, as well
as from their common parent-form, the Gallus bankiva; and these
characters are faithfully transmitted by each breed to their offspring
at the corresponding periods of life. For instance, the chickens of
spangled Hamburgs, whilst covered with down, have a few dark spots on
the head and rump, but are not striped longitudinally, as in many other
breeds; in their first true plumage, they are beautifully pencilled,
that is each feather is transversely marked by numerous dark bars; but
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